PI Perspective #29

April 2000     View PDF     En español

NIH Study Cautions Use of
St. Johns Wort with Anti-HIV Drugs

A study conducted by the National Institutes of Health (NIH) found a significant interaction between the popular herbal therapy, St John’s Wort (Hypericum perforatum), and the protease inhibitor, indinavir (Crixivan). Indinavir blood levels were substantially decreased when the two drugs were used together, greatly reducing indinavir’s anti-HIV activity. This can quickly lead to the development of resistance to indinavir. Individuals commonly use St. Johns Wort as a mild anti-depressant.

St. John’s Wort is also likely to significantly decrease blood levels of some other protease inhibitors as well as non-nucleoside reverse transcriptase inhibitors. People who take these drugs are advised not to use St. Johns Wort. Similar problems with drug interactions may occur between St. John’s Wort and medications used to treat other life-threatening illnesses, such as heart disease.

One possible limitation of the current finding is that it is not clear how it applies to the various forms of St. John’s Wort on the market. Because they are completely unregulated, there is no way of knowing how much St. John’s Wort is actually present, or the quality of the product. Other preparations may have a stronger or weaker effect. Also, the methodology of the study has not been fully described yet.

As this study illustrates, there’s a definite potential for some herbal and nutritional supplements to lower the effectiveness of anti-HIV drugs or other medications. Individuals who use complementary therapies should always discuss possible interactions with their doctors and pharmacists.